Radio receiving station



Dec. 11, 1928. 1,695,175

H. F. LOWENSTEIN RADIO RECEIVING STATION Filed June 25, 192.4

Patented Dec. 11, 1928.

UNITED STAT-ESP PATENT OFFICE.

HARRY F. LGWENSTEIN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO EDWARD E. COLLADAY, OF WASHINGTON, DISTRICT OF COLUMBIA. I

RADIO RECEIVING STATION,-

Application med June 25, 1924. Serial 110,722,361.

The present invention relates to subscribers station circuits and apparatus for combined radio and wired radio receiving systems in which current is supplied to the sub- 'scribers for operation of their radio sets with a combined telephone and radio tele-- phone system in which the telephone system is of the usual centralized battery or common battery type. Where such centralized battery system is used in the-combination, a constant potential is maintained on the lines, so that when the telephones are not in use, the radio telephones can be adjusted so as to function properly-on the telephone circuit using the metallic circuit only, without substation grounds; However, when the telephone transmitter which is of low resistance is bridged across the line a drop of potential occurs at the subscribers station due to the series resistance of the-line which must'be compensatedfor in order" to maintain roper function of the subscribers radio telephone apparatus especially with respect to the filament current and plate'potential.

I attain my object by providing at the subscribers radio telephone station a source of current of sufiicient potential and current supplying capacit to compensate for the drop in potential ue to the bridging-of the telephone transmitter across the line and restrict the use of current from said local source for this purpose byproviding means past the local source to the subscribers radio telephone or from the line to the local source, 7

butpreventing the flow of current from the local source to the line, which enables the local source to supply sufilcient energy to compensate for the potential dropwithout the necessity of having to abnormally increase the flow ofcurrent through the current consuming device such as the telephone receiver in order to satisfy the equation of Ohms law,'E-RC. 4

A preferred form of my invention is illustrated in the accompanying drawings, in which:

Fig. is a simplified or schematic diagram of the invention in its simplest form.

Fig. 2 1s a diagram showlng the invention applied to a combined radio telephone and telephone exchange system using common battery supply. I I

Referring to the drawings in detail and first to Flg. 1, 1 is a radio telephone receiv- 1ng set having an audion tube or similar electron discharge device 2. 3 and 4 represent a' pair of line wiressueh as those of the telephone line supplied with current from a constant potential source such as the,

battery The line, wire 4 extends directly to the circuits of the receiving set l'while the line wire 3 is extended through an electrolytic rectifier 5 to the plus bus wire 6 of the radio telephone set 1. A telephone set T is connected across the line 3 -4 with the usual switchhook 7 for opening and closing its transmitter circuit across the line, WhlCh circuit consists of the usual induction coil winding 8, switchhook contacts 9 and 7, and transmitter 10, The horizontal distance between the vertical dotted lines separating the battery B from the telephone set T represents the indefinite or variable distance between the battery B located at the telephone central station and the telephone and other apparatus located at the subscribers station. The plate 11 of the discharge device 2 is directly connected with the conductor 6 while the filament 12-is4con'nected through resistance 13 and choke coil 14 to the plus conductor -6, at its plus terminal, and has its minus terminal connected directly to the minus line conductor 4. Bridged across the conductors 4 and 6 is a -local source of current B referably in the permitting current to flow from the line form of a storage battery 0 a potential substantially. equal to or less than that of the primary source B. As the battery of the usual common battery telephone exchange system is about 25 volts, this voltage is chosen for the battery "B in the present instance so that the voltage of the battery B will also be substantially equal to or slightly less than 25 volts and the filament resistance 13 is adjusted to supply the proper operating current to the filament 12, the full voltage between the conductors 6 and 4; being supplied to the plate-filament circuit. The rectifier 5 is connected in the circuit 3-6 to permit the flow of current thereover only in a direction as indicated by the arrow 15.

In operation, assuming the telephone T to be disconnected from the line as shown, the full voltageof the primary battery B will be maintained on the conductors 6-4, by virtue of the direct connection of conductor 4 with the minus side of battery B and connection of the conductor 6" through rectifier 5 and line wire3 with the plus terminal of the battery B, and as t e rectifier 5 ermits current to ass in t e direction 0% the arrow 15 the lament 12 will be supplied by current from the main battery B over line wire 3, rectifier 5, conductor 6, choke coil 14, resistance 13,. filament 12, and back over line wire 4to battery B. It is found in practice that under such conditions very little or no current is supplied by the battery B and that the plate voltage, or voltage between the conductors 6-4, is substantially the full line voltage. The subscribers radio telephone circuit 1 is thus maintained properly energized for reception of radio signals in the receiving device R, which may be the usual telephone headset. When the telephone set T is brought into use by raising the switchhook 7 the circuit and its transmitter 10 is connected across the line wires 3-4, by way of induction coil winding 8 and the switchhook contacts 97, and as the resistance of the transmitter is comparatively low, there will be a drop in the line potential due to the flow of current therethrough and through the line and its resistance; Due to the presence of the secondary battery B the normal difi'erence of potential between the conductors 6'-4 will be maintained by said secondary battery; from which energy will not be draWn' 'by the transmitter T because of-the presence of the rectifier or current valve 5. Energy draft from the battery B is thus limited to the requirements of the subscribers radio tele phone receiver 1. The term secondary as applied to the battery B is simply indicative of its relation to the main battery B and it is to be understood that it may take the form of any type of current source such as a rimar batter secondary or 'stora e P y y t 3 battery, or dynamo generator. It is preferable touse a storage battery for the battery B in which case it will. receive charging current from the main battery when the switch-hook? is down and the telephone T is disconnected from theline.

Fig. 2 shows a more complete system embodying the invention in which the circuits and apparatus to the right of the dotted lines 17 represent that portion of the system situated at the central ofiice-of a common battery telephone exchange system, while battery B with which connection is made through the operators cord circuit 20 having tip and sleeve conductors 21 and 22 for connecting the common battery B to the tip and sleeve multiple conductors 23 and 24, respectively, on the subscribers, line. The operators cord cirucit 20 is also provided with a listening key 25 for connecting the operators .34 terminate in multiple jacks 18 and 19 telephone headset 26 with the cord conductors. The line wires 3-4 are connectedat the subscribers station with the subscribers telephone set T in the usual manner and are also connected with the terminal of a radio telephone jack 27 by which headset R included in series with ,a feedback coil 32 in the plate circuit. Conductors 36 and 34 are the current supply conductors for the radio telephone set and correspond to the conductors 64 of Fig. 1, except that instead of being permanently connected to. the line through rectifier 5, they are connected to the line in SGIlGSWltll the rectifier 5 through radio plug 28, the conductor 34 being directly connected with the sleeve terminal of the radio plug and the 'condue tor 26 connected with the tip terminal through the rectifier 5 and conductor 33. The battery B is a storage battery of substantially the same voltage as that of the and has its plus terminal connected to the tip conductor 36 and its minus terminal connected to the sleeve conductor 34, so as to be in oppositionto the main battery B which is similarly connected to the tip and sleeve conductors of the cord 20. The output or plate circuit of the subsc'ribers radio telephone set is thus connected across'the tip and sleeve, or plus and minus conductors 36 and 34 and the plus ment 12, and conductor 34 back to battery.

B The filament 12 is also connected across the conductors 36 and 34 but in series with an impedance coil '14, and resistance 13'.

The rectifier 5 is connected to pass current in the direction of the arrow 15 and to facilitate passage of the voice or telephone currents therethrough its terminals may be bridged by a condenser 35.

With the radio plug 28 removed from itsjack 27, the connections between the subscribers station and the telephone central station are substantially the same as that of the usual commonbattery telephone exchange system, the subscribers line circuit being open when the receiver hook is down as indicated in the drawing. With the radio telephone plug 28 of this jack 27 and the central station common battery B connected to the line through the plug 37 and multiple jack 18, the subscribers radio set 1 is supplied with current from the main battery B over the following path: Battery B, tip or plus cord ,oonductor 21, plug and jack connection 37-18, line wires 3, jack and plug connection 2728, conductor 33, rectifier 5, plus conductor 36 through plate and filament circuits of the subscribers radio telephone set to conductor 34, and thence through plug and jack connection 2827, linewire 4, jack and plug connection 1837, tip cord conductor 22 and back to the main battery 13.

As the voltage of thesecondary battery B is substantiallythe same or less than that of the main battery very little or no current is supplied by it to the radio telephone set. When the telephone T is brought into use byraising its switchhook 7, the transmitter 10 is connected across the line through -con-' ductor' 39, induction coil winding8, contacts 9-7, transmitter 10, and conductor 40.

This produces a drop in potential across the line conductors 3-4, which, however, will not draw current from the secondary'battery B due to the current valve 5 which prevents the flow of current from the plus side of this battery back over the conductors 36 and 33 to the line conductor 3. The subscribers radio telephone set is now supplied with current fromthe secondary battery 13 During non-use of both the radio telephone 1 and the telephone T the secondary battery 13 may be charged from the main battery B by opening the .switch 38 and leaving the radio telephone set 'con-' nected to line through the plug and jack con.-

nection 28-27. The charging circuit may be traced from the plus terminal of main battery l3, over conductor 21, plug and jack connection 37-48, line wire 3, jack and plug connection 2728, conductor 33, rectifier 5, conductor 36, secondary battery B conductor 34, plug and jack connection 28- 27, line conductor 4. plug and jack connection 18-37, and conductor 22 back to the minus terminal of the main battery B. By thus preventing the fiow of ener from-the local battery back into the line, its energy is not only conserved but exces- 'when the telephone is disconnected from the line current will be supplied to the radio telephone set from the main battery B over the line through the rectifier 5 with but slight drop in potential due to the small amount of current taken by the filament 12 through the line resist-ance,'and if the voltage of the secondary battery B is substantially equal, to the resulting voltage across the conductors 36-34 it will simply be floated on the line and supply no energy thereto.

Thus if the battery is designed to give this voltage fully charged it will recharge during use of the radio set whenever it is slightly below charge but always give cur-.

rent to the radio set whenever the telephone transmitter 10 is connected across the line. While a specific embodiment of the invention is herein shown and described for the purpose of disclosure, it is to be understood that the invention is not limited to such specific embodiment but contemplates all such variations and modifications thereof as fairly fall within the scope of the appended claims. For example, anyform of rectifier may be used in place of the electrolytic rectifier shown, and other formsof source of current may be used in place of the battery. shown. 1 Having thus described the invention, what is claimedand desired to be secured by Letters Patent is: 1. In a'combined radio receiving and telephone system, a pair of line wires, a central ofiice source of current supply for said linewires, a subscribers telephone of relatively low resistance connected to said line wires,. a subscribersradio receiving set of relatively high resistance also connected to said, line wires, means for supplying current from said central source to either or both of said instruments over the line wires, a local booster storage battery connected across the line wires between said instruments and a currentvalve connected in one of said lines Wires between the telephone and the radio receiving set in a manner to prevent discharge of current from said storage battery-to said telephone while permitting the flow of current from said telephone to both the storage battery and the radio receiving set.

2. In a combined radio receiving and telephone system, a pair of line wires, a central otiice source of current supply for said line wires, a subscribers telcp one of relatively .low resistance connected to said line wires, a subscribers radio receiving set of relatively high resistance also connected to subscribers radio receiving set, but to opsaid line Wires, a subscribers local storage pose the discharge of the local battery battery connected to be charged overthe line through the s'ubscribers telephone. 10 and to supply current to the subscribers In testimony whereof I-hereunto affixmy radio receiving set only and a current valve signature.

connected to permit the flow ofcurrent from l the line to'botli said storage battery and HARRY F. LOWENSTEIN. 

